Periodic Disordered Breathing Detection

Abstract

Systems and methods are directed to evaluating breathing disorders, such as periodic disordered breathing. A signal representative of patient respiration is developed, typically patient-internally. An envelope of the signal is provided. Periodicity of the envelope is detected, and presence and severity of periodic disordered breathing is determined based on the periodicity of the envelope.

1 . A system, comprising:
 an implantable housing;   detection circuitry provided in the housing and configured to detect a signal representative of patient respiration; and   a processor configured to detect periodicity of an envelope of the signal and determine presence of periodic disordered breathing based on the periodicity of the envelope by computing a parameter characterizing envelope cycle length for multiple envelope cycles occurring within a time window, the parameter comprising one or both of a standard deviation (K SD ) of duration for n envelope cycles and the predetermined duration divided by a mean (K MEAN ) indicative of average envelope cycle length, wherein n is a number.   
     
     
         2 . The system of  claim 1 , wherein the processor is configured to detect regularity of envelope periodicity. 
     
     
         3 . The system of  claim 1 , wherein the processor is configured to determine presence of periodic disordered breathing by determining regularity of envelope periodicity and a duration of envelope cycles occurring within the time window of predetermined duration. 
     
     
         4 . The system of  claim 1 , wherein the processor is configured to determine a duration of envelope periodicity. 
     
     
         5 . The system of  claim 1 , wherein the processor is configured to determine envelope periodicity if the standard deviation (K SD ) is less than a first threshold and n is greater than a second threshold. 
     
     
         6 . The system of  claim 1 , wherein the processor is configured to determine presence of periodic disordered breathing if the standard deviation (K SD ) is less than a first threshold, n is greater than a second threshold, and K MEAN  falls within a third threshold range. 
     
     
         7 . The system of  claim 1 , wherein the processor is configured to compute an estimated apnea-hypopnea index based on the periodicity of the envelope. 
     
     
         8 . The system of  claim 1 , wherein the processor is configured to compute an estimated apnea-hypopnea index based on a number of periodic disordered breathing events occurring within each of a plurality of the time windows, a total duration of the plurality of time windows defining a duration of patient sleep. 
     
     
         9 . The system of  claim 1 , wherein the processor is configured to determine severity of the periodic disordered breathing. 
     
     
         10 . The system of  claim 1 , wherein the processor is configured to determine severity of the periodic disordered breathing at least in part by distinguishing between central sleep apnea and obstructive sleep apnea. 
     
     
         11 . The system of  claim 1 , wherein the processor is configured to determine severity of a patient's heart failure condition by determining presence of the periodic disordered breathing in each of a plurality of physiological states. 
     
     
         12 . The system of  claim 1 , wherein the processor is configured to determine severity of the periodic disordered breathing at least in part by determining a frequency of the periodicity and a stability of the periodicity. 
     
     
         13 . The system of  claim 1 , wherein the processor is configured to determine severity of the periodic disordered breathing at least in part by determining a depth of a change in peaks of the envelope. 
     
     
         14 . A system, comprising:
 an implantable housing;   a respiration sensor;   detection circuitry provided in the housing and coupled to the respiration sensor, the detection circuitry configured to detect a signal representative of patient respiration;   conditioning circuitry provided in the housing and coupled to the detection circuitry, the conditioning circuitry configured to (a) remove a trend or a DC component of the signal representative of patient respiration and rectifying the signal or (b) square and low pass filter the signal representative of patient respiration; and   a processor communicatively coupled to the conditioning circuitry, the processor configured to detect periodicity of an envelope of the signal and determine presence of periodic disordered breathing based on the periodicity of the envelope.   
     
     
         15 . The system of  claim 14 , wherein the processor is configured to detect periodicity of the envelope of the signal and determine presence of periodic disordered breathing by computing a parameter characterizing envelope cycle length for multiple envelope cycles occurring within a time window. 
     
     
         16 . The system of  claim 14 , wherein the processor is configured to:
 detect periodicity of the envelope of the signal and determine presence of periodic disordered breathing by computing a parameter characterizing envelope cycle length for multiple envelope cycles occurring within a time window; and   compute an estimated apnea-hypopnea index based on a number of periodic disordered breathing events occurring within each of a plurality of the time windows, a total duration of the plurality of time windows defining a duration of patient sleep.   
     
     
         17 . The system of  claim 14 , wherein the processor is configured to compute a parameter characterizing envelope cycle length for multiple envelope cycles occurring within the time window, the parameter comprising one or both of a standard deviation (K SD ) of duration for n envelope cycles and the predetermined duration divided by a mean (K MEAN ) indicative of average envelope cycle length, wherein n is a number. 
     
     
         18 . The system of  claim 14 , wherein the processor is configured to:
 determine severity of the periodic disordered breathing at least in part by determining a frequency of the periodicity and a stability of the periodicity; or   determine severity of the periodic disordered breathing at least in part by determining a depth of a change in peaks of the envelope.   
     
     
         19 . The system of  claim 14 , wherein the processor is configured to distinguish between central sleep apnea, obstructive sleep apnea, and hypopnea. 
     
     
         20 . A system, comprising:
 means for developing a signal representative of patient respiration from within a patient;   means for detecting periodicity of an envelope of the signal; and   means for determining presence of periodic disordered breathing based on the periodicity of the envelope by computing a parameter characterizing envelope cycle length for multiple envelope cycles occurring within a time window, the parameter comprising one or both of a standard deviation (K SD ) of duration for n envelope cycles and the predetermined duration divided by a mean (K MEAN ) indicative of average envelope cycle length, wherein n is a number.